If your site loads slow you have to increase memory_limit
Read https://docs.woothemes.com/document/increasing-the-wordpress-memory-limit/
For clear Woocommerce it needs to be minimum 64M. For VC plugin developers recommend 128M
If you use 40M it can slow down your site
php settings must be
1 | php_value upload_max_filesize 64M |
2 | php_value post_max_size 64M |
3 | php_value max_execution_time 3000 |
4 | php_value max_input_time 3000 |
Also read http://www.onlinemediamasters.com/slow-wordpress-admin-panel/